Identification and distribution of the clinical isolates of imipenem-resistant Pseudomonas aeruginosa carrying metallo-β-lactamase and/or class 1 integron genes

Abstract

To investigate the distribution of the genes of two major metallo-β-lactamases (MBL; i.e., IMP and VIM) and class 1 integrons (intI) in the clinical imipenem-resistant Pseudomonas aeruginosa, a total of 65 isolates, from a university hospital in Sichuan between December 2004 and April 2005 were screened for MBL genes by PCR using primers specific for bla_IMP-1, bla_VIM and bla_VIM-2 genes. The MBL-positive isolates were further assessed for class 1 integrons by PCR using specific primers. The nucleotide sequences of several PCR products were also determined. The results revealed that the bla_VIM gene was found in 81.5% (53/65) of all isolates, bla_VIM-2 gene was found in only 1 isolate and the intI gene was observed in 45.3% (24/53) of bla_VIM-positive isolates. One isolate carried simultaneously both bla_IMP-1 and intI genes, and to the best of our knowledge this is the first report of such isolate in southwest China. These observations highlight that the genes for VIM β-lactamase and class 1 integrons were predominantly present among the imipenem-resistant P. aeruginosa tested, confirming the current widespread threat of imipenem-resistant, integron-borne P. aeruginosa.

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Huazhong University of Science and Technology and Springer-Verlag GmbH